Dielectric properties of water trees

The present study looks into the dielectric behavior of water trees. Wet water trees have much higher conductivities than dry water trees and than PE. This is assigned to the dependence of ion mobility on the presence of water. Voltage dependent effects are found. These results are related to two important issues. Firstly, a voltage dependent conductivity explains why DC-testing of water trees insulation is dangerous. Secondly, the voltage dependent ion conductivity of water trees opens gates to successful diagnostics for water tree detection in cables.